/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: fzykd
 * Date: 2022-03-03
 * Time: 16:22
 */
class ListNode{//代表一个节点
    public int val;
    public ListNode next;

    public ListNode(int val){
        this.val=val;
    }
}

public class MyLinkedList {
    public ListNode head;//链表的头引用

    public void createList(){//创建链表的方法
        ListNode listNode1=new ListNode(12);
        ListNode listNode2=new ListNode(23);
        ListNode listNode3=new ListNode(34);
        ListNode listNode4=new ListNode(45);
        ListNode listNode5=new ListNode(56);
        ListNode listNode6=new ListNode(67);


        listNode1.next=listNode2;
        listNode2.next=listNode3;
        listNode3.next=listNode4;
        listNode4.next=listNode5;
        listNode5.next=listNode6;//相当于手动拼接

        this.head=listNode1;
    }


    public void display(){//遍历链表
        ListNode cur=this.head;
        while (cur!=null){
            System.out.print(cur.val+" ");
            cur=cur.next;
        }
        System.out.println();
    }



    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key){
        ListNode cur=this.head;
        while (cur != null){
            if (cur.val==key){
                return true;
            }
            cur =cur.next;
        }
        return false;
    }


    //得到单链表的长度
    public int size(){
       ListNode cur=this.head;
       int count=0;
       while (cur!=null){
           count++;
           cur=cur.next;
       }
       return count;
    }



    //头插法
    public void addFirst(int data){
        ListNode node=new ListNode(data);
        node.next=this.head;
        this.head=node;
    }
    //尾插法
    public void addLast(int data){
        ListNode node=new ListNode(data);
        if (this.head==null){
            this.head=node;
        }else {
            ListNode cur=this.head;
            while (cur.next!=null){
                cur=cur.next;
            }
            cur.next=node;
        }
    }

    /**
     * 找到index-1位置节点的地址
     * @param index
     * @param
     */
    public ListNode findIndex(int index){
        ListNode cur=this.head;
        while (index-1!=0){
            cur=cur.next;
            index--;
        }
        return cur;
    }



    //任意位置插入,第一个数据节点为0号下标
    public void addIndex(int index,int data){
        if (index<0||index>size()){
            System.out.println("index位置不合法");
        }
        if (index==0){
            addFirst(data);
            return;
        }
        if (index==size()){
            addLast(data);
            return;
        }
        ListNode cur=findIndex(index);
        ListNode node=new ListNode(data);
        node.next=cur.next;
        cur.next=node;
    }

    /**
     * 找到 要删除关键字的前驱
     * @param key
     */
    public ListNode searchPerv(int key){
        ListNode cur=this.head;
        while (cur.next!=null){
            if(cur.next.val==key){
                return cur;
            }
            cur=cur.next;
        }
        return null;
    }


    //删除第一次出现关键字为key的节点
    public void remove(int key){
        if (this.head==null){
            System.out.println("单链表为空，不能删除！");
            return;
        }
        if (this.head.val==key){
            this.head=this.head.next;
            return;
        }
        ListNode cur=searchPerv(key);
        if (cur==null){
            System.out.println("没有你要删除的节点");
            return;
        }
        ListNode del=cur.next;
        cur.next=del.next;
    }

     //删除所有值为key的节点
     public ListNode removeAllKey(int key){
        if (this.head==null) return null;

        ListNode prev=this.head;
        ListNode cur=this.head.next;
        while (cur!=null){
            if (cur.val==key){
                prev.next=cur.next;
                cur=cur.next;
            }else {
                prev=cur;
                cur=cur.next;
            }
        }
        //最后处理头节点
         if (this.head.val==key){
             this.head=this.head.next;
         }

        return this.head;
     }


     public void clear(){
        //this.head==null
         while (this.head!=null){
             ListNode curNext=head.next;
             this.head.next=null;
             this.head=curNext;
         }
     }

}
